1. Field of the Invention
The present invention is generally related to a pressure controlling device for an internal combustion engine and, more particularly, to a poppet that is overmolded to provide an improved sealing surface so that cooling water within an internal combustion engine of a marine propulsion system can be more accurately controlled.
2. Description of the Prior Art
It is well known to those skilled in the art that it is beneficial to regulate the pressure within the cooling system of an internal combustion engine in addition to regulating the temperature.
U.S. Pat. No. 5,937,802, which issued to Bethel et al on Aug. 17, 1999, discloses an engine cooling system which is provided with coolant paths through the cylinder block and cylinder head which are connected in serial fluid communication with each other. In parallel with the cooling path through the cylinder head, a first drain is connected in serial fluid communication with a pressure responsive valve and the path through the cylinder block. A temperature responsive valve is connected in serial fluid communication with the cylinder head path and in parallel fluid communication with the first drain. A pump is provided to induce fluid flow through the first and second coolant conduits and the first and second drains, depending on the pressure responsive valve and the temperature responsive valve.
U.S. Pat. No. 6,481,418, which issued to Ristich et al on Nov. 19, 2002, describes a fuel pressure regulator. A fuel pressure regulator for supplying fuel to the intake of an internal combustion engine at a substantially constant pressure is provided. The fuel pressure regulator includes a housing defining a fuel chamber in fluid communication with a fluid inlet. The housing further includes a fuel outlet opening in fluid communication with the fuel chamber. The housing defines a seating surface around the outlet opening. A valve body is moveably disposed within the housing and moves between open and closed positions. The valve body contact and seals against the seating surface and prevents fuel flow through the outlet opening when the valve body is in the closed position. The valve body is biased into the closed position. The valve body includes an extension with at least a portion thereof disposed in the fuel outlet opening to guide the valve body.
U.S. Pat. No. 3,918,418, which issued to Horn on Nov. 11, 1975, discloses a marine engine cooling system employing a thermostatic valve means and a pressure relief valve means. A pressure relief valve for an engine of an outboard motor includes a valve plate connected to a stem and spring loaded water cooling passageway in closed spaced relation to a thermostatically controlled valved passageway. The stem extends outwardly through a water discharge chamber directly in communication with the discharge passageway to the lower unit of the motor. A diaphragm is connected to the out end of the valve stem and is sealed to form a wall of the water discharge chamber. The discharge chamber is normally under a slight water discharge pressure whenever the thermostatic valve is open and thus creates a very slight pressure on the diaphragm which is balanced by the closure spring until such time as the pump pressure within the cooling system is sufficient to overcome the force of the spring. As the relief valve opens, the internal passageway pressure is transmitted to the discharge chamber. This results in the diaphragm rapidly moving outwardly and establishing the full open position of the relief valve. This, in turn, results in a reduction of the internal passageway pressure.
The technique of overmolding an object with either plastic or an elastomeric material is well known to those skilled in the art. Various techniques and processes have been developed to perform this overmolding procedure. In addition, many different objects have been manufactured through the use of an overmolding process.
U.S. Pat. No. 6,537,853, which issued to Johnson et al on Mar. 25, 2003, describes an overmolding encapsulation process. A method of encapsulating an article having first and second surfaces, including positioning the articles on a carrier such that at least a portion of the first surface contacts the carrier is described. A portion of the carrier carrying the article is then positioned within a mold and a seal is formed between the mold and the carrier. The mold is then filled with an encapsulating material to form a seal between the article and the carrier.
U.S. Pat. No. 5,588,202, which issued to Ehlers et al on Dec. 31, 1996, discloses a method for manufacturing an overmolded sensor. A method is described for manufacturing a plurality of proximity sensors which are attached to a printed circuit board during the manufacturing steps and subsequently severed from the printed circuit board by shearing. Each of the proximity sensors comprises a core and coil assembly, a plurality of electronic components and an electrical connector. These components of each of the proximity sensors is encapsulated during an overmolding process and the encapsulations are removed from the printed circuit board by a shearing step. Each of the encapsulations can be inserted into a cylindrical housing.
U.S. Pat. No. 6,523,380, which issued to McGuire et al on Feb. 25, 2003, describes an overmolded key including an ornamental element and method of making same. A vehicle ignition key having an ornamental element molded onto the key is described. The key includes a key blank and an undermold which is formed by molding a first plastic material over a portion of the key blank, defining a mounting surface for the element. The ornamental element is located on the mounting surface and secured to the heel portion of the key blank by an overmold which is formed by molding a second plastic material over the heel portion of the key blank, the undermold, and at least a portion of the element. In one embodiment, the overmold material covers substantially the entire peripheral edge of the element.
U.S. Pat. No. 6,116,884, which issued to Rowley et al on Sep. 12, 2000, describes a mold core for overmolded flexible valves. A mold core is provided for producing an overmolded flexible valve. The mold core comprises a mold body, a piston assembly, a piston retaining means, a collet bit positioning means and at least two collet bits. The mold core has a cylindrical void in a distal end and has a pressure means communicated with the cylindrical void. The piston assembly has a piston head sized and adapted for axial movement in the cylindrical void, with a piston shaft extending axially from the head. The shaft is tapered from a larger first diameter at one end to a smaller second diameter at the other end. The piston retaining means has a bore through it to allow insertion of the piston shaft. Each of the at least two collet bits has an inner cylindrical tapered surface segment, the taper of the surface segment being essentially the same as the taper of the piston shaft, and an out cylindrical surface segment, sized and adapted to be inserted inside the flexible valve. The at least two collet bits are positioned adjacent to the tapered portion of the shaft. The collet bits are positioned by the collet bit positioning means.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
If the poppet does not successfully prevent the flow of coolant from the cooling passage to the drain passage when the pressure within the cooling passage is less than a predetermined threshold magnitude, cooling liquid will flow out of the cooling passage and be replaced by colder cooling fluid. In a marine propulsion system, the replacement liquid is water from a body of water in which a marine vessel is operating. Typically, this water is much colder than the water within the cooling passage as the internal combustion engine operates.
In cases where the poppet does not properly seal to block the conduit, the engine operates at a temperature which is less than the optimal, or desired, temperature. Therefore, it is important to make sure that the poppet properly seals the conduit when the coolant in the cooling passage is at a pressure less than the preselected pressure for which the pressure regulating device was chosen. It would therefore be significantly beneficial to the operation of a marine engine if a poppet could be provided which assures proper sealing of the conduit when the coolant pressure is less than the predetermined pressure.